Good:
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I really liked a Montbell thermawrap jacket, about all the warmth layer needed for the whole trip; I added a thermawrap vest for the Sierras but scarcely needed it.
20F WM bag until end of the Sierras then swapping to a WM 32F (both down) bag, worked perfectly.
Poncho as both shelter and raingear for first 700 miles was great, tarptent thereafter (more for bugs than rain on the PCT).
Smartphone as multifunction device, including using this my only camera and an infrequently used GPS, but also journaling device, internet (weather and trail reports).
Actual glacier glasses in the Sierras.
Neutral:
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Solio solar charger — worked well in SoCal to augment charging in town, less well as I moved north, should have stopped carrying when I got into Oregon.
SMC Snow/Sand stake as potty trowel (and backup stake): generally good, but aluminum stake sometimes bent, not as strong as I would like.
Integral Designs Hot Socks for the Sierras: Okay, but I'm not overwhelmed by the warmth to weight ratio relative to just carrying a thick spare pair of wool socks. I'll use Feathered Friends down booties on the CDT next year.
Rocky goretex socks: Overall I liked these at times in the snow, but somewhat mixed; just an extra pair of wool socks might be a better choice for the weight. I'll probably bring these again on the CDT, however.
Bad:
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Chrome dome umbrella: I never found a hands-free approach I liked, plus sometimes wind made this tricky to use, and I use two trekking poles.
I got two platypus "holster" type 1-liter water carriers to put some water weight load on my waist belt for the early part; these turned out to be a PITA, came off whenever I put the pack down, jabbed into me a bit (the carry hook).
Monocular: nice idea, I just almost never used it and so mailed it home.
Mini-crampons: didn't need, not worth carrying. For that matter, in 2008 a lot of people (me included) mailed ice axe home before finishing the Sierras.